# US 5,705,403 A · Method of measuring doping characteristic of compound semiconductor in real time

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- Number: US 5,705,403 A
- Document ID: US5705403A
- Status: Granted
- Kind: A
- Application number: 08/696,092
- Filed: 1996-08-13
- Granted: 1998-01-06
- Earliest claimed: 1995-12-20
- Assignees: Electronics and Telecommunications Research Institute
- Inventors: Jong-Hyeob Baek; Bun Lee; Jin-Hong Lee; Sung-Woo Choi
- Web page: https://patentgrep.com/patent/US5705403A

## CPC

- H10P 14/3444: {P-type}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/2911: {Arsenides}
- H10P 14/3221: {Arsenides}
- H10P 14/3421: {Arsenides}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of sensing the concentration of a doped impurity on a semiconductor in real time and a method of sensing the change of its growth rate dependent on time among the changes of the growing conditions due to doping by using a real time analysis apparatus in growing a heterostructured semiconductor by a MOCVD method. A reflecting signal during the growth by means of a real time analysis apparatus has a periodic property, an amplitude change of a reflecting signal is dependent on an absorption coefficient when an absorption exists on an epitaxial layer, an impurity concentration can be obtained by using the relation of an absorption coefficient and an impurity concentration. In addition, if each peak is independently analyzed, the respective growth rate dependent on time are measured individually, so that the reduced growth rate dependent on time of the growth rate is sensed in a carbon doped AlAs layer.

## Claims

### Claim 1

A method of sending the doping characteristic of a compound semiconductor in real time, said method comprising the steps of:
epitaxially growing a compound semiconductor in a growth chamber of an epitaxy apparatus;
injecting a reactive gas in said growth chamber;
growing a heterostructure compound semiconductor layer;
simultaneously scanning a He--Ne laser beam and a diode laser beam from a laser apparatus onto the surface of a compound semiconductor in said growth chamber;
analyzing a laser beam reflected and a refraction ratio of an epitaxial layer; and
analyzing the doping concentration and growth rate of a compound semiconductor grown in real time.

### Claim 2 (depends on 1)

The method according to claim 1, wherein said growth rate is obtained by the formula of G.lambda./2nT, wherein G is the growth rate .lambda. is a wavelength of a laser, n is an effective refractive index of an epitaxial layer grown, and T is a period of a reflecting signal.

### Claim 3 (depends on 1)

The method according to claim 1, wherein said heterostructure compound semiconductor is performed by an epitaxy process of two steps of forming an AlAs layer and a GaAs layer.

### Claim 4 (depends on 2)

The method according to claim 2, wherein said growth rate is obtained by using any one of a He--Ne laser or a diode laser.

### Claim 5 (depends on 1)

The method according to claim 1, wherein said doping characteristic is measured by an absorption coefficient of a laser beam of a grown epitaxial layer.